Orthodontic treatment involves movement of malpositioned teeth to orthodontically correct positions. Tiny orthodontic appliances, known as brackets, are connected to anterior, cuspid and bicuspid teeth, and an archwire forms a track to guide movement of the teeth to desired positions. In previous years, the orthodontic appliances were connected to teeth by welding or brazing each orthodontic appliance to a metal band, which was then placed on the desired tooth. But, more recently, it has been preferred to bond the brackets directly to the tooth surface. The direct bonding method minimized the use of metal band thus eliminating the “metallic mouth” appearance that is often associated with orthodontic treatment.
The use of a bonding method may typically require, among other steps, placing an amount of orthodontic adhesive on the bracket, applying the brackets to the desired, preferably preconditioned teeth, and removing excess orthodontic adhesive. Conventional orthodontic adhesives are typically clear or contain pigment, which gives the orthodontic adhesives a white or tooth color. It is desirable that a sufficient but not an excess amount of orthodontic adhesive is used to bond the brackets to the teeth surface. Excess orthodontic adhesive on the teeth may eventually be a site for bacteria accumulation. Because orthodontic treatment may last from 18 to 36 months or more, the bacteria accumulation may damage the teeth and may lead to discoloration of the orthodontic adhesive, both of which may be undesirable. Removal of the excess orthodontic adhesive from teeth surfaces may be difficult if there is similarity in the orthodontic adhesive color and the teeth color due to a lack of a contrasting color in the orthodontic adhesive.
Orthodontic adhesives with high bond strengths may lead to other difficulties. For example, one of the most difficult aspects of the orthodontic treatment process may be the removal of the bracket after completion of treatment. It is well known in the industry that certain adhesives, used in combination with certain rigid brackets, are capable of causing enamel fracture under some debonding conditions. As a result, many commercially available ceramic brackets have been designed for the bond to fail at the interface between the bracket and the adhesive to prevent damage to the tooth surface during the debonding process. This approach results in most of the cured adhesive pad being left behind on the tooth surface after the bracket has been removed. Removal of the adhesive pad, which is typically hard and heavily crosslinked, may be time consuming for the clinician and uncomfortable for the patient.
As with the unhardened orthodontic adhesive, the removal of the cured orthodontic adhesive from teeth surfaces may be difficult if there is similarity in the cured orthodontic adhesive color and the teeth color due to a lack of a contrasting color in the orthodontic adhesive.
A need remains for a method that effectively distinguishes unhardened and/or hardened orthodontic adhesive from the tooth surface to enable easy removal of the orthodontic adhesive by the practitioner.